Extracorporeal Treatment with High Intensity Focused Ultrasound of an Incompetent Perforating Vein in a Patient with Active Venous Ulcers.

INTRODUCTION: Endovenous techniques such as ultrasound guided foam sclerotherapy, thermal methods, or glues are generally recommended to occlude incompetent veins. However, these methods can be technically challenging and risky for patients with severe atrophic skin disorders like lipodermatosclerosis or atrophie blanche. High intensity focused ultrasound (HIFU), which has been shown to coagulate and occlude veins successfully, may offer an alternative method. This case report details ultrasound guided HIFU to occlude non-invasively a refluxing perforator vein causing active ulcers. REPORT: A 95 year old man presented to the Institute for Functional Phlebology (Melk, Austria) with painful recurrent ulcers in his left medial calf. His limb was scored C2,3,4a, b,6, Ep, Ap, Pr,18 according to the Clinical, Etiology, Anatomic, Pathophysiology (CEAP) classification. Lower limb ultrasound revealed a refluxing posterior tibial perforating vein, measuring 2.7 mm in diameter at the level of the fascia. Extracorporeal HIFU pulses were delivered to this vein with the Sonovein device (Theraclion, Malakoff, France). Sonication was applied for eight seconds at a mean acoustic power of 80 W. The patient was followed up for three months post-treatment and occlusion was evaluated by duplex ultrasound. There were no complications during treatment or follow up. Three months after the treatment, reflux was abolished and the two initially active ulcers had healed. DISCUSSION: Although this is an early report, this study shows that HIFU can be successful in ablation of incompetent perforator veins in the treatment of venous leg ulcers.

Vein wall shrinkage induced by thermal coagulation with high-intensity-focused ultrasound: numerical modeling and in vivo experiments in sheep.

BACKGROUND: Varicose veins are a common disease that may significantly affect quality of life. Different approaches are currently used in clinical practice to treat this pathology. MATERIALS AND METHODS: In thermal therapy (radiofrequency or laser therapy), the vein is directly heated to a high temperature to induce vein wall coagulation, and the heat induces denaturation of the intramural collagen, which results macroscopically in vein shrinkage. Thermal vein shrinkage is a physical indicator of the efficiency of endovenous treatment. High-intensity focused ultrasound (HIFU) is a noninvasive technique that can thermally coagulate vein walls and induce vein shrinkage. In this study, we evaluated the vein shrinkage induced in vivo by extracorporeal HIFU ablation of sheep veins: six lateral saphenous veins (3.4mm mean diameter) were sonicated for 8 s with 3MHz continuous waves. Ultrasound imaging was performed before and immediately post-HIFU to quantify the HIFU-induced shrinkage. RESULTS: Luminal constriction was observed in 100% (6/6) of the treated veins. The immediate findings showed a mean diameter constriction of 53%. The experimental HIFU-induced shrinkage data were used to validate a numerical model developed to predict the thermally induced vein contraction during HIFU treatment. CONCLUSIONS: This model is based on the use of the k-wave library and published contraction rates of vessels immersed in hot water baths. The simulation results agreed well with those of in vivo experiments, showing a mean percent difference of 5%. The numerical model could thus be a valuable tool for optimizing ultrasound parameters as functions of the vein diameter, and future clinical trials are anticipated.

Efficacy and safety assessment of an ultrasound-based thermal treatment of varicose veins in a sheep model.

Purpose: Varicose veins are a common pathology that can be treated by endovenous thermal procedures like radiofrequency ablation (RFA). Such catheter-based techniques consist in raising the temperature of the vein wall to 70 to 120 °C to induce vein wall coagulation. Although effective, this treatment option is not suited for all types of veins and can be technically challenging.Materials and methods: In this study, we used High-Intensity Focused Ultrasound (HIFU) as a non-invasive thermal ablation procedure to treat varicose veins and we assessed the long-term efficacy and safety of the procedure in a sheep model. In vivo experiments were first conducted on two saphenous veins to measure the temperature rise induced at the vein wall during HIFU ablation and were compared with reported RFA-induced thermal rise. Thermocouples were inserted in situ to perform 20 measurements during 8-s ultrasound pulses at 3 MHz. Eighteen saphenous veins of nine anesthetized sheep (2-2.5 % Isoflurane) were then exposed to similar pulses (85 W acoustic, 8 s). After treatments, animals recovered from anesthesia and were followed up 30, 60 and 90 days post-treatment (n = 3 animals per group). At the end of the follow-up, vein segments and perivenous tissues were harvested and histologically examined.Results: Temperatures induced by HIFU pulses were found to be comparable to reported RFA treatments. Likewise, histological findings were similar to the ones reported after RFA and laser-based coagulation necrosis of the vein wall, thrombotic occlusions and vein wall fibrosis.Conclusion: These results support strongly the effectiveness and safety of HIFU for ablating non-invasively veins.